1. Field
This disclosure relates to hydrogen producing fuel cartridges, and methods for producing hydrogen from these cartridges.
2. General Background
World-wide commercial use of fuel cell powered host devices, particularly portable devices. A non-exclusive list of potential host devices include, but are not limited to, computer peripherals, mobile phone peripherals, mobile phones, personal music players, laptops, notebooks, tablet, gaming devices, personal digital assistants (PDAs), and battery chargers. A fuel cell power system can either be located inside the host device or can be connected to the host device using suitable means. In either case, a means to provide fuel to the power system is required. An example of one such means is the use of fuels packaged in cartridges (packaged fuel) in predetermined amounts to satisfy the volume, weight and run time requirements of the host device, use profile of the host device, and regulatory requirements associated with the host device. For the sake of simplicity, a fuel cell power system is considered to comprise of a fuel cell subsystem that includes the fuel cell or a multiplicity of fuel cells in the form of a fuel cell stack, fluid, and power management means, a process controller, and the fuel cartridge. The fuel cartridge is connected to the fuel cell subsystem system using a connector or coupling.
Hydrogen can be produced by hydrolysis of chemicals such as sodium borohydride. Fuel cartridges for producing hydrogen from sodium borohydride are disclosed in U.S. Pat. Nos. 7,794,886, 7,832,433, 7,896,934 and 8,002,853. Hydrogen production from hydrolysis is characterized by short start-up times and good control of hydrogen production rates. However the need to use water or other aqueous solutions decreases the hydrogen storage capacity of these fuel cartridges. In addition, once activated to support a fuel cell system, hydrogen continues to evolve from these cartridges requiring a buffer to store this hydrogen in the event the fuel cell system is shut-off.
Hydrogen may be produced via thermolysis of chemicals such as ammonia borane and alane (aluminum hydride). For example, US2010/0226829A1 describes a hydrogen generator that produces hydrogen by the decomposition of ammonia borane. In a thermolysis fuel cartridge, hydrogen is produced by supplying heat to the chemicals contained in the fuel cartridge.
Accordingly, it is a desideratum to develop designs, components and methods to improve thermal management and hydrogen production efficiencies in thermolysis fuel cartridges for use in fuel cell power systems.